Operation mechanism of switch having three positions of operation

Abstract: In an operation mechanism of a switch having three positions of operation, when a first driving crank (42) is rotated and is engaged with a recess (41C) of a driven lever (41) at a roller disposed on the crank, revolution of a second driving crank (52) is obstructed by a plate member (42G) mounted on the first driving crank. In a similar manner, when the second driving crank is rotated and is engaged with the recess of the drive lever, the revolution of the first driving crank is obstructed by a plate member (52G) of the second driving crank. Therefore, even if the first driving crank or the second driving crank is erroneously operated, erroneous operation of the switch is prevented.

Description: FIELD OF THE INVENTION AND RELATED ART STATEMENT 1. FIELD OF THE INVENTION The present invention relates generally to an operation mechanism for a switch, and particularly to an operation mechanism for a switch having three positions of operation of "disconnection", "connection" and "ground", for example. 2. DESCRIPTION OF THE RELATED ART In an operation mechanism for a switch having three positions of operation, three positions of rotation of a rotating shaft are predetermined to operate the switch, and the three positions of rotation correspond to "disconnection", "connection" and "ground" of the switch, for example. In the operation mechanism of the switch having three positions of operation in the prior art, the known Geneva mechanism, one of intermittent rotating apparatus, is incorporated in the above-mentioned rotating shaft. The Geneva mechanism is composed of a Geneva gear and a driving crank, and the Geneva gear is intermittently rotated by a predetermined angle at every revolution of the driving crank. The above-mentioned rotating shaft is connected to the Geneva gear, and is rotated by the predetermined angle at every revolution of the driving crank. The three positions of rotation of the rotating shaft made by three revolutions of the driving crank correspond to the "disconnection", "connection" and "ground" of the switch, respectively. In the operation mechanism of the switch having three positions of operation in the prior art, the Geneva gear is rotated by one driving crank. Therefore, if a target position of the three positions is mistaken for wrong position or if the rotating direction of the driving crank is mistaken, the switch is incorrectly operated. Another operation mechanism for a switch, which discloses the pre-characterising features of claim 1, is known from JP-A-05 054 747. OBJECT AND SUMMARY OF THE INVENTION An object of the present invention is to provide an operation mechanism for a switch having three positions of operation which is provided with means for preventing incorrect operation of the switch. The operation mechanism for a switch having three positions of operation in accordance with the present invention comprises: a rotating shaft adapted to be connected to an operation shaft of the switch having three positions of operation, a driven lever comprised of a plate member perpendicularly connected to the rotating shaft, having a recess formed from an end of the plate member toward the rotating shaft on a center line passing through the rotating shaft and a first arc-shaped concave and a second arc-shaped concave which are formed symmetrically with respect to the center line on the end portion, a first driving shaft and a second driving shaft pivotally mounted at symmetrical positions with respect to the center line at a predetermined reference position of the driven lever, a first driving crank mounted on the first driving shaft, comprising a roller for engaging with the recess of the driven lever by revolution of the first driving shaft, and an arc-shaped convex member for engaging with the first arc-shaped concave of the driven lever, a second driving crank mounted on the second driving shaft, comprising a roller for engaging with the recess of the driven lever by revolution of the second driving shaft, and an arc-shaped convex member for engaging with the second arc-shaped concave of the driven lever, characterised by a semicircular member mounted on each of the first and second driving shafts first stopper means for limiting an angle of clockwise revolution of the first driving crank from the reference position to a predetermined value, and second stopper means for limiting an angle of counterclockwise revolution of the second driving crank from the reference position to a predetermined value, and whereby in the state that the roller of the first driving crank is engaged with the recess of the driven lever, a semicircular part of the semicircular member mounted on the first driving shaft opposes close to a straight part of the semicircular member mounted on the second driving shaft so as to block rotation of the second driving crank, and in the state that the roller of the second driving crank is engaged with the recess of the driven lever, a semicircular part of the semicircular member mounted on the second driving shaft opposes close to a straight part of the semicircular member mounted on the first driving shaft so as to block rotation of the first driving crank. When the roller of the first driving crank engages with the recess of the driven lever, rotation of the arc-shaped member of the second driving crank is prevented, because the arc-shaped part of the arc-shaped member disposed on the driving shaft of the first driving crank opposes close to a straight part of the arc-shaped member mounted on the driving shaft of the second driving crank. In a similar manner, when the roller of the second driving crank engages with the recess of the driven lever, revolution of the arc-shaped member of the first driving crank is prevented by the arc-shaped member of the second driving crank. While the novel features of the invention are set forth particularly in the appended claims, the invention, both as to organization and content, will be better understood and appreciated, along with other objects and features thereof, from the following detailed description taken in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG.1 is a side view of an embodiment of an operation mechanism of a switch having three positions of operation of the present invention; FIG.2 is a II - II cross-section of FIG. 1; FIG.3 is a perspective view of a driven lever; FIG.4 is a perspective view of a first driving crank; FIG.5 is a perspective view of a second driving crank; FIG.6 is a II - II cross-section of FIG.1 representing disconnection state of the operation mechanism of the switch having three positions of operation; FIG.7 is a II - II cross-section of FIG.1 representing connection state of the operating mechanism of the switch having three positions of operation; FIG.8 is a II - II cross-section of FIG.1 representing the connection state of the operation mechanism of the switch having three positions of operation; FIG.9 is a II - II cross-section of FIG.1 representing ground state of the operation mechanism of the switch having three operation positions. It will be recognized that some or all of the Figures are schematic representations for purposes of illustration and do not necessarily depict the actual relative sizes or locations of the elements shown. DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.1 is a side view of an embodiment of the operation mechanism of a switch having three positions of operation in accordance with the present invention, and FIG.2 is a II - II cross-section of FIG. 1. Referring to FIG.1, a frame 43 is composed of a front plate 43A and a rear plate 43B which are arranged in parallel, and a distance between the front plate 43A and the rear plate 43B is kept constant by spacers 43C. A driven lever 41 composed of an oval metal plate and secured to a rotating shaft 41A at an end part is pivotally mounted in the interior of the frame 43. A detailed structure of the driven lever 41 is shown in FIG.3 which is a perspective view. The rotating shaft 41A of the driven lever 41 is connected to a moving part 40A of the switch 40 having three positions of operation, and thereby the switch 40 is operated. The driven lever 41 is provided with a U-shaped recess 41C on the center line X as shown in FIGs. 2 and 3. A first arc-shaped concave 41D and a second arc-shaped concave 41J are formed in symmetry with respect to the center line X. The driven lever 41 is also provided with semicircular recesses 41E, 41F and 41G in the vicinity of the rotating shaft 41A. A first driving crank 42 shown in FIG.4 and a second driving crank 52 shown in FIG.5 are disposed in the interior of the frame 43. Referring to FIG.4, the first driving crank 42 is comprised of a fan-shaped plate member 42G fixed on the driving shaft 42A, a substantially rectangular plate member 42H and a fan-shaped convex member 42F sandwiched by both the plate member 42G and the plate member 42H. The recess of the convex member 42F, as described in detail hereinafter, is cut in order not to contact the end of the driven lever 41 which is rotated by the driving crank 42. The central angle of the convex member 42F is about 240 degrees in the embodiment. A roller 42E is pivotally mounted by a shaft 42D at the end part between the plate members 42G and 42H. Distance between centers of the driving shaft 42A and the shaft 42D is equal to a distance in perpendicular direction between the central line X and the center of the driving shaft 42A in the state that the driven lever 41 is placed at a position shown in FIG.2 (hereinafter is referred to as a first position). Referring to FIG.5, the second driving crank 52 is substantially identical with the driving crank 42 except for difference in the shape of the plate member 52H from the plate member 42H. The central distance between the driving shaft 52A and the shaft 52D is equal to the perpendicular direction between the center of the driving shaft 52A and the center line X in the state that the driven lever 41 is placed at the first position. When the driven lever 41 is positioned at the first position as shown in FIG.2, the driving shafts 42A and 52A are positioned at the symmetrical positions with respect to the center line X. Radius of curvatures of the convex members 42F and 52F of the driving cranks 42 and 52 are substantially equal to the radius of curvatures of the arc-shaped concaves 41D and 41J of the driven lever 41. In rotating operation of the driving crank 42 or the driving crank 52, if the revolution angle exceeds a predetermined range, the plate members 42H and 52H serve to obstruct rotation of the driving crank 42 or 52 by contacting to the respective stopper pins 36A and 39A disposed on the front frame 43A of the frame 43. In the embodiment, the driving crank 42 is driven by an electric motor 42B and the driving crank 52 is driven by manual operation, for example. Hereafter, operation of the embodiment is described. Now, the position of the driven lever 41 in FIG.2 is defined as the first position, and the first position shows an initial state. The switch having three positions of operation is configured to be disconnected in the first position, for example. In the initial state shown in FIG.2, the convex members 42F and 52F of the first and second driving cranks 42 and 52 are engaged with the arc-shaped convex 41D and 41J of the driven lever 41, respectively. At the first position, the first driving crank 42 contacts the stopper pin 36A at the straight part 42K of the plate member 42H, and a clockwise revolution is obstructed. Moreover, at that time the second driving lever 52 contacts the stopper pin 39A at the straight part 52K of the plate member 52H, and a counterclockwise revolution is obstructed. As shown in FIG.6, the driving crank 42 is rotated counterclockwise, the roller 42E of the driving crank 42 is engaged with the recess 41C of the driven lever 41, and the arc-shaped convex member 42F of the driving crank 42 leaves the arc-shaped convex 41D of the driven lever 41. In this state, since the plate member 42G of the first driving crank 42 opposes close to the straight part 52I of the plate member 52G of the second driving crank 52, if the second driving crank 52 is intended to be rotated clockwise, the straight part 52I touches of the circular periphery of the plate member 42G, and can not be rotated. Thus, as a conclusion, the second driving crank 52 can not be rotated in any direction by the stopper pin 39A and the plate member 42G. When the first driving crank 42 is further rotated counterclockwise as shown in FIG.7, a torque of the first driving crank 42 is given to the driven lever 41 through the roller 42E and the face of the recess 41C, and the driven lever 41 is rotated clockwise. Finally, the revolution of the driven lever 41 is blocked by the stopper pin 35. The first driving crank 42 is further rotated counterclockwise, and the roller 42E leaves the recess 41C, and the arc-shaped convex member 42F of the first driving crank 42 is engaged with the arc-shaped concave 41J of the driven lever 41. The position of the driven lever 41 in this state is called a "second position", and the switch 40 is connected. If the motor 42B rotates counterclockwise by inertia, the driving crank 42 is blocked by touching of the stopper pin 36A to the straight part 42I of the plate member 42H as shown in FIG.8. In order to return the driven lever 41 from the second position to the first position, the first driving crank 42 is rotated clockwise. Subsequently, in order to rotate the driven lever 41 from the first position as shown in FIG.2 to a third position as shown in FIG.9, only the second driving crank 52 is rotated clockwise. When the second driving crank 52 is rotated clockwise, the roller 52E of the second driving crank 52 is engaged with the recess 41C of the driven lever 41. At this position, the arc-shaped convex member 52F of the second driving crank 52 leaves the arc-shaped concave 41J of the driven lever 41. When the roller 52E of the second driving crank 52 reaches immediately before the position to engage with the recess 41C of the driven lever 41, in a similar relation to that in FIG.6, the plate member 52G of the second driving crank 52 oppose close to the straight part 42I of the plate member 42G of the first driving crank 42, and counterclockwise revolution of the first driving crank 42 is obstructed. Thus, the first driving crank 42 can not be rotated in any direction by the stopper pin 36A and the plate member 52G. When the second driving crank 52 is further rotated clockwise, a torque of the second driving crank 52 is given to the driven lever 41 through the roller 52E and the face of the recess 41C, and the driven lever 41 is rotated counterclockwise. Finally, as shown in FIG.9, the second driving crank 52 is blocked by meeting the stopper pin 39A at the straight part 52I of the plate member 52H. Consequently, revolution of the driven lever 41 stops. The position of the driven lever 41 is called a "third position". In the third position, the switch is operated to be grounded. In order to return the driven lever 41 from the third position to the first position, the second driving crank 52 is rotated counterclockwise by manual operation, for example. As shown in FIGs.2 and 3, the driven lever 41 is provided with three recesses 41E, 41F and 41G in the vicinity of the rotating shaft 41A corresponding to the above-mentioned first position, second position and third position, respectively. Openings 43E for inserting a stopper rod 60 are formed in the front plate 43A and the rear plate 43B of the frame 43. The driven lever 41 is interlocked by inserting the stopper rod 60 in the opening 43E at a desired position of the above-mentioned first, second or third position as shown in FIGs. 1 and 9. The stopper rod 60 is inserted in the opening 43E for preventing unexpected rotation of the driven lever 41 in maintenance work or repair operation of the switch 40. According to the embodiment of the present invention, when the first driving crank 42 is rotated in a direction, for example counterclockwise, and the roller 42E is engaged with the recess 41C of the driven lever 41, then revolution of the second driving crank 52 is prevented by the plate member 42G of the first driving crank 42 because the semicircular part of the plate member 42G of the first driving crank 42 opposes close to the straight part 52I of the plate member 52G of the second driving crank 52. Therefore, revolution of the second driving crank 52 is blocked, and erroneous operation of the second driving crank 52 is prevented. In a similar manner, when the second driving crank 52 is rotated clockwise and the roller 52E is engaged with the driven lever 41, revolution of the plate member 42G of the first driving crank 42 is blocked by the plate member 52G of the second driving crank 52 because the semicircular part of the plate member 52G of the second driving crank 52 opposes close to the straight part 42I of the plate member 42G of the first driving crank 42. Consequently, erroneous operation of the first driving crank 42 or the second driving crank 52 is prevented, and hence the erroneous operation of the switch is also prevented.

Claims: An operation mechanism for a switch having three positions of operation, said mechanism comprising: a rotating shaft (41A) adapted to be connected to an operation shaft of said switch having three positions of operation, a driven lever (41) comprised of a plate member perpendicularly connected to said rotating shaft, having a recess (41C) formed from an end of said plate member toward said rotating shaft on a center line (X) passing through said rotating shaft and a first arc-shaped concave (41D) and a second arc-shaped concave (41J) which are formed symmetrically with respect to said center line on the end portion, a first driving shaft (42A) and a second driving shaft (52A) pivotally mounted at symmetrical positions with respect to said center line (X) at a predetermined reference position of said driven lever (41), a first driving crank (42) mounted on said first driving shaft (42A), comprising a roller (42E) for engaging with said recess (41C) of said driven lever (41) by revolution of said first driving shaft (42A), and an arc-shaped convex member (42F) for engaging with said first arc-shaped concave (41D) of said driven lever, a second driving crank (52) mounted on said second driving shaft (52A), comprising a roller (52E) for engaging with said recess (41C) of said driven lever by revolution of said second driving shaft (52A), and an arc-shaped convex member (52F) for engaging with said second arc-shaped concave (41J) of said driven lever, characterised by a semicircular member (42G, 52G) mounted on each of said first (42A) and second (52A) driving shafts, first stopper means (36A) for limiting an angle of clockwise revolution of said first driving crank (42) from said reference position to a predetermined value, and second stopper means (39A) for limiting an angle of counterclockwise revolution of said second driving crank (52) from said reference position to a predetermined value, and whereby in the state that said roller (42E) of said first driving crank is engaged with said recess (41C) of said driven lever, a semicircular part of said semicircular member (42G) mounted on said first driving shaft opposes close to a straight part (52I) of said semicircular member (52G) mounted on said second driving shaft so as to block rotation of the second driving crank (52), and in the state that said roller of said second driving crank (52E) is engaged with said recess (41C) of said driven lever, a semicircular part of said semicircular member (52G) mounted on said second driving shaft opposes close to a straight part (42I) of said semicircular member (42G) mounted on said first driving shaft so as to block rotation of the first driving crank (42). An operation mechanism for a switch having three positions of operation in accordance with claim 1, wherein said driven lever (41) is provided with three recesses (41E, 41F, 41G) corresponding to three revolution positions, a frame (43) holding said driven lever is provided with openings 43E, and a stopper rod (60) is inserted through one of said three recesses and said openings so as to prevent rotation of the driven lever in maintenance work or repair operation.

Inventors: INOUE TAKAKAZU, INOUE, TAKAKAZU, INOUE, TAKAKAZU, C/O MITSUBISHI DENKI K. K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1994
Main classification: H01H3
IPC codes: H01H3, H01H31, H01H33